Re: [PATCH v3 2/9] staging: iio: ad2s1200: Improve readability with be16_to_cpup

[Jonathan Cameron <jic23@kernel.org>]

On Mon, 23 Apr 2018 00:03:03 +0200
David Veenstra <davidjulianveenstra@gmail.com> wrote:

> The manual states that the data is contained in the upper 12 bits
> of the 16 bits read by spi. The code that extracts these 12 bits
> is correct for both be and le machines, but this is not clear
> from a first glance.
> 
> To improve readability the relevant expressions are replaced
> with equivalent expressions that use be16_to_cpup.
> 
> Signed-off-by: David Veenstra <davidjulianveenstra@gmail.com>
Looks good to me.

Applied to the togreg branch of iio.git and pushed out as testing
for the autobuilders to play with it.

Thanks,

Jonathan

> ---
> Changes in v3:
>  - change type of rx to __be16.
>  - remove unneeded variable vel.
>  - remove unneeded type cast to s16 (patch line 79).
> 
>  drivers/staging/iio/resolver/ad2s1200.c | 11 ++++-------
>  1 file changed, 4 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/staging/iio/resolver/ad2s1200.c b/drivers/staging/iio/resolver/ad2s1200.c
> index 17d65cb437fd..998f458dc1bd 100644
> --- a/drivers/staging/iio/resolver/ad2s1200.c
> +++ b/drivers/staging/iio/resolver/ad2s1200.c
> @@ -47,7 +47,7 @@ struct ad2s1200_state {
>  	struct spi_device *sdev;
>  	int sample;
>  	int rdvel;
> -	u8 rx[2] ____cacheline_aligned;
> +	__be16 rx ____cacheline_aligned;
>  };
>  
>  static int ad2s1200_read_raw(struct iio_dev *indio_dev,
> @@ -58,7 +58,6 @@ static int ad2s1200_read_raw(struct iio_dev *indio_dev,
>  {
>  	struct ad2s1200_state *st = iio_priv(indio_dev);
>  	int ret = 0;
> -	s16 vel;
>  
>  	mutex_lock(&st->lock);
>  	gpio_set_value(st->sample, 0);
> @@ -68,7 +67,7 @@ static int ad2s1200_read_raw(struct iio_dev *indio_dev,
>  	gpio_set_value(st->sample, 1);
>  	gpio_set_value(st->rdvel, !!(chan->type == IIO_ANGL));
>  
> -	ret = spi_read(st->sdev, st->rx, 2);
> +	ret = spi_read(st->sdev, &st->rx, 2);
>  	if (ret < 0) {
>  		mutex_unlock(&st->lock);
>  		return ret;
> @@ -76,12 +75,10 @@ static int ad2s1200_read_raw(struct iio_dev *indio_dev,
>  
>  	switch (chan->type) {
>  	case IIO_ANGL:
> -		*val = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
> +		*val = be16_to_cpup(&st->rx) >> 4;
>  		break;
>  	case IIO_ANGL_VEL:
> -		vel = (((s16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
> -		vel = sign_extend32(vel, 11);
> -		*val = vel;
> +		*val = sign_extend32(be16_to_cpup(&st->rx) >> 4, 11);
>  		break;
>  	default:
>  		mutex_unlock(&st->lock);